Radiation Hormesis in Humans Exposed to Low Level Ionizing Radiation

Through various researches and investigations it has been established that high doses of ionizing radiation are harmful to health. There is substantial controversy regarding the effects of low doses of ionizing radiation despite the large amount of work carried out (both laboratory and epidemiological). According to the linear no-threshold (LNT) hypothesis, any amount, however small, of radiation is potentially harmful, even down to zero levels. The threshold hypothesis, on the other hand, emphasizes that below a certain threshold level of radiation exposure, any deleterious effects are absent. At the same time, there are strong arguments, both experimental and epidemiological, which support the radiation hormesis (beneficial effects of low-level ionizing radiation). These effects cannot be anticipated by extrapolating from harmful effects noted at high doses. The choice of the approximate dose-response model for use in estimating the health effects of small doses of ionizing radiation remains controversial. In the present work, a comprehensive study of the available literature, data and reports of various radiation exposure and protection studies is presented. In conclusion, we find that the radiation hormesis contradicts the predictions made by the LNT hypothesis regarding the health effects of ionizing radiation in the low dose region.